Subtraction


Once again, work with tens and get use to these ;

10
-
9
=
1
10
-
8
=
2
10
-
7
=
3
10
-
6
=
4
10
-
5
=
5

 

To do calculations (when the answer is not obvious), borrow 10 from the tens column and place it in the units column.

Subtraction Algorithm 1

This allows you to see the 0 of 30 as 10.
Then 10 – 5 = 5 (As you have learnt.)
The 1 you borrowed from the tens column can be taken from the 3.

ubtraction Alogorithm 2

If you find numbers hard to subtract , expand 17 to give the digits their place value 17 = 10 + 7.
Now you can go 10 – 8 = 2 then add on the 7 to get 9.

 

When subtracting larger numbers the same method applies ;

Subtraction Algorithm3

Work on your subtraction with the Maths Polisher.